7 replies to this topic

[Apogeefoods]

Good morning,

 

We just had a screw housing break in one of our extruder machines, and our maintenance guy ordered a new part fabricated from cast iron. He said it was okay for food contact, we just have to keep it coated in oil to prevent it from rusting. Does anyone know if cast iron is okay for food contact? It's not like a cast iron pan that you might be used to, the surface is very smooth and well-finished. The extrusion is generally a cold process but sometimes the machine can heat up if it has to work harder to extrude a particularly difficult product. The part isn't typically lubricated on the food contact surface, most of the products are wet enough to act as the lubricant themselves, and when lubrication is necessary, we use canola oil. I appreciate any feedback you guys can give me!

 

Thanks,

Caleb

[dstout]

There shouldn't be any reason you can't use cast iron, but watch out for that rust because the surfaces typically oxidize over time. There may be a food grade coating that you can look into as well epoxies and others etc. 

[SQFconsultant]

Cast iron for a food application is intended as a cooking surface only.

 

You would need to have a constant surface material coating running to prevent rust and oxidation.

 

What was the original material that it was made out of?

 

I can not give you the exact code but I found this at one time -- 

 

The FDA’s Food Rule notes that cast-iron equipment is only approved for use in the food industry for cooking surfaces and in utensils for serving food “if the utensils are used only as part of an uninterrupted process from cooking through service.”

For all other uses, cast iron MAY NOT BE USED as a food-contact surface. Iron without a protective material is simply too vulnerable to corrosion and oxidation.

[kettlecorn]

Glenn is correct. The FDA Food Code he is citing can be found here: https://www.fda.gov/...110822/download

 

What follows is the language in full: 

 

4-101.12 Cast Iron, Use Limitation.

(A)

Except as specified in ¶¶ (B) and © of this section, cast iron may not be used for UTENSILS or FOOD-CONTACT SURFACES of EQUIPMENT.

(B)

Cast iron may be used as a surface for cooking.

©

Cast iron may be used in UTENSILS for serving FOOD if the UTENSILS are used only as part of an uninterrupted process from cooking through service. 

[Gway]

We've cast Iron twin screw mechanisms in one of our extruders which as long as it it lubricated appropriately has caused no issues. Accepted here as long as release values within defined levels of accepatability 

[Parkz58]

Perhaps I'm being a little glib here, but next time your maintenance guy says something is OK for food contact, stop and stare him straight in the eyes and say "show me where it says that".

 

OK, enough about that (my own frustrations from past dealings with maintenance are showing through too much)...the root question of all of this is simply, why would you use cast iron parts in an extruder?  I don't understand the logic...at all.

[Apogeefoods]

The part was originally made from plastic, I'm not sure what type. We had an issue where the screws got misaligned somehow and the plastic housing got gouged somewhere in the process and left plastic shavings that were discovered upon cleaning. We had no idea when the issue happened, and we sent off some of the plastic pieces to an x-ray company and they couldn't detect it, so we ended up having to throw away a whole day's worth of product. We wanted a new housing made of metal to prevent it from happening again and for some reason our machine shop suggested cast iron.

[mgourley]

Perhaps have the same part machined out of stainless steel?

I certainly would not use cast iron as a "part".

 

Marshall